Variations in prey consumption of centipede predators in forest soils as indicated by molecular gut content analysis

Abstract

Predation is an important ecological factor driving animal population structures, community assemblages and consequently ecosystem stability and biodiversity. Many environmental factors influence direction and intensity of predation, suggesting that trophic linkages between animals vary between different habitats. This in consequence has particular relevance in anthropogenically altered habitats such as managed forests, where disturbance regime, tree composition and stand age may change the natural food web structure. We investigated how prey consumption of three common centipede predators (Lithobius spp., Chilopoda), representing two body sizes varies between four differently managed forest types in two regions across Germany. We hypothesized that prey preference of these generalist predators is independent of forest type but rather driven by habitat structure, prey abundance and predator body size. Applying specific PCR assays to test for DNA of three abundant prey groups, i.e. Collembola, Diptera and Lumbricidae, in the predators’ guts, we tracked trophic interactions. The results showed that management type indeed has no influence on centipede prey consumption but depth of litter layer and soil pH. Trophic interactions varied between the two sampled forests regions mainly due to changes in the detection of Lumbricidae and Diptera. Also, effect of litter layer and prey abundance significantly differed between the smaller L. crassipes and the larger L. mutabilis, indicating a body size effect. The results complement food web analyses using fatty acids and stable isotopes by elucidating trophic interactions in soil in unprecedented detail.

Unravelling the complex structure of forest soil food webs: higher omnivory and more trophic levels

“…Overall, we found only few effects of the land‐use types on food‐web topology. Most of these effects could readily be assigned to the dominant tree species that cause different litter types (needles vs leaf litter) and habitat structures (Ferlian and Scheu , Günther et al ). This suggests that the structure of soil food webs is relatively robust against variation in forest types.…”

Shifts in trophic interactions with forest type in soil generalist predators as indicated by complementary analyses of fatty acids and stable isotopes

“…Similarly, closely related species of lithobiids and geophilomorphs have been found to be trophically distinct with trophic niches in lithobiid species even varying between life stages presumably due to the ability of larger individuals to catch large mobile prey (Ferlian et al ). Using molecular gut content analysis, Günther et al () also found that Lithobius mutabilis and Lithobius crassipes differ in the frequency of feeding on lumbricid prey with the differences being associated with differences in body size. In the present study, the trophic separation of these two species was mainly due to bacterial marker FAs being high in L. crassipes and low in L. mutabilis , suggesting that L. crassipes is more strongly associated with the bacterial energy channel as compared to L. mutabilis .…”

“…As indicated by molecular gut content analysis, lithobiids mainly prey on collembolans, lumbricids and Diptera larvae (Günther et al ). As indicated by FA composition, the former two predominantly feed on fungi/bacteria (Ruess et al ) and the latter on bacteria (Ferlian unpubl.).…”

“…The head capsule including antennae and the hind part were used for stable isotope analysis and FA analysis, respectively. The mid part was used for molecular gut content analysis (Günther et al ).…”

“…stable isotope ( 13 C and 15 N) and FA analysis, for analysing variations in the trophic position and association to fungal versus bacterial energy channels, respectively, in the two differently sized centipede species L. mutabilis and L. crassipes . Further, in a parallel study employing molecular gut content analysis, links between these two predator species and prey taxa were identified (Günther et al ). We hypothesised that trophic niches of the two centipede species vary with forest type due to differences in habitat structure.…”